This invention relates to fanner magnet assemblies.
Fanner magnets are used to fan out or separate the sheets in a stack of metal sheets so that the sheets may be picked up by suitable transfer devices such as suction cups for movement to another location where the sheets may be processed by suitable processing equipment. The magnets operate on the principle of disparate polarity along the vertical face of a magnet so that the individual metal sheet adjacent the top of the stack are fanned out or separated to facilitate the operation of the transfer device.
Typically, a plurality of magnets are arrayed along one side edge of the stack of sheets adjacent the top of the stack and a like plurality of magnets are arrayed along the opposite side edge of the stack of sheets adjacent the top of the stack. Typically, a stack of metal sheets is raised into position between the opposed fanner magnets, and the fanner magnets are moved into engagement with the opposite side faces of the stack adjacent the top of the stack to fan out the sheets adjacent the top of the stack to facilitate the transfer operation. As the stack is depleted, the stack is moved upwardly in incremental amounts with the fanner magnets continuing to engage the top portion of the stack as the stack is moved incrementally upwardly.
Whereas fanner magnets of this general type have proven to be generally satisfactory in facilitating the transfer operation, the prior art magnet assemblies have typically generated an error signal in the event that transversely misaligned sheets occur in the stack and the error signal has typically been utilized to withdraw all of the magnet assemblies in a ganged manner from the stack and reject the stack. After the stack has been rejected and a new stack moved upwardly in its place, the fanner magnets are again moved in gang fashion into engagement with the opposite side faces of the new stack, and the fanning and transfer operations continue. This ganged withdrawal of all of the magnet assemblies in response to an error signal and replacement of the stack is both wasteful and time consuming.